Lamp assembly

ABSTRACT

A lamp assembly for use with an arc discharge type lamp employing an external trigger wire to provide the required conductive path allowing illumination voltage to discharge through the tube.

[ Nov. 26, 1974 References Cited UNITED STATES PATENTS .1 LAMP ASSEMBLY [75] Inventors: Richard A. Orrvick, Palmyra; Ihor Kulbida, Fairport, both of NY.

NOCl et al. 313/113 x 1/1953 Lemmers....................,.......313/234 9/1972 240/5l.1l R

[73] Assignee: Xerox Corporation, Stamford,

Conn.

Hirschman May 29, 1973 Appl. No: 364,793

[22] Filed:

Primary ExaminerAlfred L. Brody [57] ABSTRACT A lamp assembly for use with an arc discharge type lamp employing an external trigger wire to provide the [52] U.S. c1.... 313/113, 240/5111 R, 240/4135 R,

1101 5/16, F2lv 7/09 313/113,234;240/51.11 R, 240/4135 R, 92 R, 103 R, 20

Int. required conductive path allowing illumination voltage to discharge through the tube.

[58] Field of Search......

4 Claims, 4 Drawing Figures LAMP ASSEMBLY BACKGROUND OF THE INVENTION In xerographic copy machines it has been the practice to illuminate the document to be copied by use of florescent lamps and utilize a scanning system to project reflected rays from the document onto a photoreceptive surface to provide a latent image thereon in conformity with the image on the document.

In order to provide higher speed copiers, the scanning speed has been increased. However, there is a practical limit to the speed at which the mechanical components of the scanning system may be operated. For high speed copying therefor, a xerographic machine having a belt type photoreceptive surface adapted for flash exposure may be employed to obviate the need for a scanning system. Due to the operating speed of the machine, the illumination system must be capable of providing intense uniform illumination of the document at extremely short intervals.

This may be accomplished by using lamps such as xenon tubes. To allow rapid discharge of xenon tube, a trigger voltage pulse is' applied externally to the tube along the wire which is held adjacent to the tube (ordinarily by wrapping the tube with the wire). This ionizes the xenon gas inside forming a conductive path and allowing the illumination power supply voltage to discharge through the tube and generate a flash. For proper illumination of the document, the tube may be utilized with suitable reflectors.

SUMMARY OF THE INVENTION This invention relates to a lamp assembly including a reflector having tubular lamp means spaced therefrom for flash illuminating a document to produce a latent electrostatic image of the document on a photoconductive surface in a reproduction machine. Clamp means are mounted on the reflector for electrically isolating and releasably securing the lamp means in spaced relation to the reflector, the clamp means being adapted to maintain a flash triggering wire parallel to and adjacent the lamp means in spaced relation from the reflector and provide isolated electrical connectors to prevent arcing from the wire to the reflector.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic sectional view of the xerographic reproduction machine employing the lamp assembly of the present invention;

FIG. 2 is a perspective view of an assembled lamp assembly;

FIG. 3 is an end view of the lamp assembly for retaining and locating the tubular lamp and the trigger wire relative to the lamp and the reflector with a portion broken away for clarity; and,

FIG. 4 is a front elevational view of one end of the lamp assembly with portions broken away for clarity.

DESCRIPTION OF THE PREFERRED EMBODIMENT For a general understanding of an electrostatic processing system in which the invention may be incorporated, reference is had to FIG. 1 in which various components of the system are schematically illustrated. As in all electrostatic systems such as a xerographic machine, a light image of an original to be reproduced is projected onto the sensitized surface of a xerographic plate to form an electrostatic latent image thereon. Thereafter, the latent image is developed with an oppositely charged developing material comprising carrier beads and smaller toner particles triboelectrically adhering thereto to form a xerographic powder image corresponding to the latent image on the plate surface. The powder image is then electrostatically transferred to a support to which it may be fixed by a fusing device whereby the powder image is caused permanently to adhere to the support surface.

In the illustrated machine, an original D to be copied is placed upon a transparent support platen P fixedly arranged in an illumination assembly generally indicated by the reference numeral 10. While upon the platen the illumination system flashes light rays upon the original thereby producing image rays corresponding to the informational areas on the original. The image rays are projected by means of an optical system 11 to an exposure station A for exposing the photosensitive surface of a moving xerographic plate in the form of a flexible photoconductive belt 12. In moving in the direction indicated by the arrow, prior to reaching the exposure station A, that portion of the belt being exposed would have been uniformly charged by a corona device 13 located at a belt run extending between belt supporting rollers 14 and 15. The exposure station extends between the roller 14 and a third support roller 16.

The exposure of the belt surface to the light image discharges the photoconductive layer in the area struck by light, whereby there remains on the belt a latent electrostatic image in image configuration corresponding to the light image projected from the original on the support platen. As the belt surface continues its movement, the electrostatic image passes around roller 16 and through a developing station B located at a third run of the belt wherein there is positioned a developing apparatus generally indicated by the reference numeral 17. The developing apparatus 17 comprises a plurality of brushes which carry material to the adjacent surface of the upwardly moving inclined photoconductive belt 12 in order to provide development of the electrostatic image.

The developed electrostatic image is transported by the belt 12 to a transfer station C located at a point of tangency on the belt as it moves around roller 15 whereat a sheet of copy paper is moved at a speed in synchronism with the moving belt in order to accomplish transfer of the developed image. There is provided at this station a transfer roller 18 which is arranged on the frame of the machine for contacting the non-transfer side of each sheet of copy paper as the same is brought into transfer engagement with the belt 12. The roller 18 is electrically biased with sufficient voltage so that the developed image on the belt 12 may be electrostatically transferred to the adjacent side of a sheet of paper as the same is brought into contact therewith.

There is also provided a suitable sheet transport mechanism adapted to transport sheets of paper seriatim from paper handling mechanisms 20 and 21 to the developed image on the belt as the same is carried around the roller 15. A programming device (not shown) operatively connected to the paper handling mechanisms and the illumination device is effective to present a developed image at the transfer station C in timed sequence with the arrival'of a sheet of paper.

After the sheet is stripped from the belt 12 it is conveyed by the stripper transport 23 into a fuser assembly generally indicated by the reference numeral 24 wherein the developed and transferred xerographic powder image on the sheet is permanently affixed thereto. After fusing, the finished copy is discharged from the apparatus at a suitable point for collection externally of the apparatus. The toner particles remainingas residue on the developed images, background particles, and those particles otherwise not transferred are carried by the belt 12 to a cleaning apparatus positioned on the run of the belt between rollers 14 and adjacent the charging device 13. The cleaning device comprises a corotron 27 for neutralizing charges remaining on the particles and a rotating brush 28 for removing the neutralized toner particles from the belt.

Referring now to FIGS. 2, 3, and 4 there is illustrated one of the reflector-lamp assemblies utilized in the i1- lumination system of the machine. The lamp 30, which is preferably a xenon tube, is mounted in spaced relation to a suitable reflector 31 to provide intense, even illumination of the document on the platen P. For a more complete description of the relationship between the lamps, the reflectors, and the platen P to provide optimum illumination of the document, reference may be had to US. Pat. application Ser. No. 270,750 filed July 11, 1972, now US. Pat. No. 3,777,135, granted Dec. 4, I973.

The tube is held in the proper spaced position relative to the reflector by suitable dielectric clamp 32 which may be secured to the reflector by means of screws 34. In order to provide adequate holding power for the screws 34 in clamp 32, a threaded metallic insert 35 may be molded or suitably retained in the clamp. Due to the high voltages supplied to the lamp through the clamp and the possibility of internal leakage to the metallic insert,-it can be seen by reference to FIG. 3 that the metallic insert 35 is recessed in the clamp so that the surfaces thereof do not contact the reflector. In conjunction with this, the screw 34 is formed of a suitable non-metallic dieletric material such as nylon to provide complete electrical isolation between the metallic insert and the reflector.

The clamp is provided with a surface 36 conforming to the curvature of the tube 30. A spring clip 38, also having a surface conforming to the curvature of the tube is provided on clamp 32 preferably by being molded therein to resiliently hold tube 30 in clamp 32. It can be seen by reference FIG. 4 that the clip 38 is molded into the clamp in spaced relation to the insert to provide adequate distance therebetween internally of the clamp to prevent possible electrical leakage therebetween and minimize the chance of internal arcing within the clamp. The spring clip 38 is formed in a generally T shape to provide a shoulder 44 thereon for reasons to be hereinafter explained. A mounting stud 40 is also provided on clamp 32 preferably by being molded therein.

In order to locate the trigger wire 42 adjacent the tube, the trigger wire is wrapped around stud 40 and sition along side and in intimate contact with the tube which is retained in the clamps by spring clips 38. The use of studs 40 for mounting the trigger wire greatly simplifies installation of the wire and proper tensioning thereof. 1 i

Due to the high voltages encountered in arc discharge type tubes, a magnetic field is generated around the tube. This magnetic field will cause the trigger wire to whip into and out of contact with the surface of the tube causing premature failure thereof if the wire is magnetic. Therefore, for extended life of the tube in the disclosed illumination system, it is desirable to employ a trigger wire constructed of non-magnetic material such as tungsten.

It can be seen by reference FIG. 3 that the tube is mounted within the reflector 30 is a position which is offset from the axis of the curved portion of the bottom of the reflector. The disclosed arrangement positions the trigger wire along side the tube at a location on the tube to provide the maximum distance possible between the trigger wire and the reflector to prevent arcing between the trigger wire and the reflector.

The reflector-clamp assembly provides a means for mounting the tube in relation to the reflector while allowing the end portions of the tube to extend beyond the reflector and clamp for adequate cooling thereof and to prevent excessive transmission of heat to the clamp. Further, by extending the tube beyond the clamp, the possibility of arcing from the electrical connections at the ends of the tube to the reflector or clamp is obviated. Suitable electrical connectors 50 are provided for connecting the ends of the tube to a suitable source of electrical power (not shown).

The trigger voltage is supplied to trigger wire 42 by a suitable wire (not shown) which is connected to studs 40 and secured thereto by suitable means such as washers 52 and nuts 54.

From the foregoing it can be seen that the lamp assembly heretofore described accurately positions the tube relative to the reflector, positions the trigger wire at an optimum location relative to the tube and the reflector to prevent arcing to the reflector when voltage is supplied to the wire for triggering the tube, allows mounting of the tube such that the heat generated at the electrical connectors thereto is not transmitted to the clamp or reflector assemblies, and minimizes the possibility of arcing between the electrical connections and the reflector or clamps.

While we have described a preferred embodiment of our invention it is to be understood that the invention is not limited thereto but may be otherwise embodied within the scope of the following claims:

What is claimed is:

l. A lamp assembly for flash illuminating a document to be reproduced on a reproduction machine comprising:

a reflector;

dielectric clamp means mounted on said reflector,

said clamp means having a contoured surface formed thereon for engagement with one side of a tubular arc discharge lamp, said clamp means inculding spring clip means disposed opposite said contoured surface, said spring clip means having a shoulder formed thereon;

a tubular arc discharge lamp, said lamp being retained in the lamp assembly between said contoured surface and said spring clip in a predetermined position relative to said reflector by said spring clip means; and

a trigger wire positioned along side said lamp parallel to the axis thereof, said wire being looped around said spring clip and retained thereon by said shoulder, said shoulder positioning said wire along side said lamp at the desired location on the periphery of said lamp relative to said reflector.

2. A lamp assembly according to claim 1 wherein said clamp means includes a wire mounting stud, said trigger wire being attached thereto, said clamp having a recess formed therein, said wire being routed from said stud through said recess around said clip under said shoulder and along side said tube.

magnetic force generated by energization of said lamp. l 

1. A lamp assembly for flash illuminating a document to be reproduced on a reproduction machine comprising: a reflector; dielectric clamp means mounted on said reflector, said clamp means having a contoured surface formed thereon for engagement with one side of a tubular arc discharge lamp, said clamp means including spring clip means disposed opposite said contoured surface, said spring clip means having a shoulder formed thereon; a tubular arc discharge lamp, said lamp being retained in the lamp assembly between said contoured surface and said spring clip in a predetermined position relative to said reflector by said spring clip means; and a trigger wire positioned along side said lamp parallel to the axis thereof, said wire being looped around said spring clip and retained thereon by said shoulder, said shoulder positioning said wire along side said lamp at the desired location on the periphery of said lamp relative to said reflector.
 2. A lamp assembly according to claim 1 wherein said clamp means includes a wire mounting stud, said trigger wire being attached thereto, said clamp having a recess formed therein, said wire being routed from said stud through said recess around said clip under said shoulder and along side said tube.
 3. A lamp assembly according to claim 2 wherein said clamp means includes a threaded metallic insert formed therein spaced from said clip, said insert being recessed from the surface of said clamp; and dielectric screw means, adapted for insertion through said reflector for threaded engagement with said insert to fasten said clamp means in position on said reflector means.
 4. A lamp assembly according to claim 1 wherein said trigger wire is formed of a non-magnetic material to prevent movement thereof relative to said lamp by the magnetic force generated by energization of said lamp. 